Photographic positive printing system



Aug. 7, 1962 R. E. BASCH PHOTOGRAPHIC POSITIVE PRINTING SYSTEM Original Filed July 21, 1954 PAPER #1 PHPER #1 F465 UP United States Patent 3,048,486. PHQTOGRAPHIC POSiTWE PRINTING SYSTEM ReiuhoidE. Bascli, Rocky Point, NY assignor toPeerless Photo Products, Inc, Shoreham, N.Y., a. corporation ofNewYork Continuation of application Serial No. 444,815; July 21, 1954.. Thisapplicationlieb. 1, 1960, Ser. No. 5,774 3 Claims. (Cl. 96-49.)

This invention relates to photographic reproductions and particularly to those yielding a reverse image on a receptive material insensitive to light. The present application is a continuation of my pending United States patent application Serial No. 444,815, filed July 21, 1954, now abandoned.

An object. of the invention is to provide a photographic system which will promptly and economically yield a positive print or an original document, drawing, picture or the like.

Further objects of the invention particularly in the special composition of the materials involved and the resultant speedy attainment of the positive print by transfer from a negative will appear from the following specification taken in connection withthe accompanying drawing in which FIG. 1 is a diagrammatic showing of an exposure making a negative by passing light through the original onto the negative;

FIG. 2 is a similar view of an exposure passing light through the negative to the original and by reflex to the face of the negative; and

FIG. 3 is a diagram illustrating the handling of the negative and positive sheets in the transfer process.

In the system illustrated inthe drawings a source 5 (FIG. l)passes light through glass 6 and original sheet" 0 ontothe negative N, the original 0 bearing characters on one side only designated 7 in contact with the lightsensitive emulsion side 3 of the negative N; The time of the exposure may be determined by trial according to the intensity of the light, the sensitivity of the emulsion 8 and the character of the original 0, and also the strength of the subsequent processing solution and the length of time it has been used.

In any event the print through? exposure is very short, usually only a few seconds.

In the reflex exposure of FIG. 2 the positions of the negative N and original 0 are reversed so that the light does not reach the negative N by passing through both sides of the original 0. Many originals will be on opaque paper or will have characters on both sides. Here the light from source 5 and glass 6 passes through the negative N and is reflected back from the original 0, the time of the exposure being determined by trial. according to the factors involved as above set forth. A typical exposure using a yellow filter is approximately seven seconds.

In either exposure of FIG. 1 or FIG. 2. the negative is separated from the original and with aminimum of exposure to light is placed face to face with. the emulsion side of the printing or positive sheet P (FIG. 3) and passed down edgewise into the processing solution 10in. tank 11 and pressed on around between guides 12 and upward together to the rubber rolls 14 squeezing out the. excess solution and pressing the sheets N, P together with the respective emulsion surfaces 8 and E in close contact;

The emulsions and processing solution are such that there is a prompt transfer of the positive image from the negative N, 8 to the lightrinsensitive emulsion. E of the positive P in a fraction of a minute, for instance twenty seconds, after which the sheets are separated and the positive P quickly dries and is ready for use.

This immediate transfer of the image to the positive print is critical to the use of the system; and. it: alone makes possible the wide adoption of the process in ofiices and'industry.

A specially ellective and prompt. cooperation is necessary between the compositions involved in order toattain this transfer. This is accomplished by first quickly difiusing the basic positive ingredients fi-omthe light-sensitive emulsion S to the light-insensitive emulsion E and then practically simultaneously and instantly developing the positive image in emulsion E.

The emulsion 8 of sheet N is of the type correspondingto photographic paper containing a silver salt. Preferably it is modified to emphasize the characteristics specially adapting it for; the present process.

A typical and preferred composition of the negative N involves the compounding and: coating procedures as follows:

22% silver nitrate in Water solution.

Compounding Procedure Ingallon Pfaudler kettle, add deionized. water, hydrochloric acid; potassium chloride, bromide. Run cold water through jacket, chilling to 25 C. with mechanical stirring.

Add gelatin. Swell A2 hour, then turn off cold? Water and turn on steam. Raise temperature to 50 C.

with mechanical stirring until solution is complete. Add a dye such as M-S-3- and an azine group desensitizer, and mix thoroughly;

Precipitation, Instructions Keep temperature of solution #1 in 100 gallon kettle; at 50-. C. with mechanical stirring throughout. Add solution #2 followed at 15 second intervals by; solutions 3 and 4. (Solutions 2, 3 and 4 at room temperature.) Immediately'turn on cold water inwater jacket. When temperature reaches 33 C., draw oil in 5 gallon kettles, 13,650 gms. per kettle for total of 28%. coating'kettles.

To apply coating the solution is melted bringing. the temperature to 45 C. and add coating agents. as follows, per-13,650:grams of emulsion:

Denatured alcohol 300 and potassium aeeaaee Water rnl 3,400 Nitrogen gm 50 Sodium sulfite anhydrous grn 600 Sodium thiosulfate 63% gm 150 Metol gm 12 Hydroquinone "gm" 90 Benzotriazole gm 12 Sodium hydroxide gm 90 Water to make 4,000 ml.

The nitrogen protects against oxidation and the sodium sulfite is also an anti-oxidant. The sodium thiosulfate acts as a solvent and is a fixer and clearer and the sodium hydroxide an 'alkalizing agent.

The emulsion 8 of negative N and the emulsion E of positive P are quickly permeated by the processing solution 10 in tank 11 conditioning the silver salt of emulsion 8 for diffusion into the emulsion layer B wherein the diffused halide is immediately transformed to a deposit of metallic silver giving the positive image.

This diffusion and transformation of the negative image of emusion 8 to the positive image of emulsion Bresults from the cooperation of emulsion 3 and the processing solution with emulsion E which is specially constituted to give the critically prompt reception and darkening of the image.

To attain this, emulsion E is carefully compounded as follows:

Solution A:

Water, deionized ml 370 Sodium hydrosulfite gm Solution B:

Water, deionized ml 200 Sodium sulfite gm 30 Make up after solution A. Gelatin solution-Prepare in 100 gallon Pfaudler kettle:

Water, deionized ml 290,000 Gelatin g 33,000 Solution #1:

Water, deionized ml 3,500 Silver sulfate gm 14 Solution #2Prepare two kettles each as follows:

Water, deionized 28 C ml 15,000 Solution A ml 170 Solution B Use after 90 minutes. Solution #3:

Ammonium chloride gm 5,000 Water, deionized ml 18,000 Solution #4:

Copper acetate 1% water solution ml 2,000 Solution #5 Water, deionized ml 2,400 Sodium hydroxide grn 6 Dissolve, then add:

Accelerator-intensifier of the type exemplified by the compound 2-amino-5-mercapto-1,3,4- thiadiazole.

The precipitating to complete the formation of the composition proceeds as follows:

Soak gelatin in water.

Melt at 50 0., cool to 40 C.

Stir and add solution #1.

Digest for 1 minute.

Add in total of 30 seconds: both kettles of solution #2. Digest for 20 minutes at 40 C. Add solution #3, solution #4, solution #5.

Stir for 2 more minutes.

Filtering through cloth draw out into 38 kettles, each kettle containing about 10,000 gm.

For coating, 10,000 gm. of the emulsion are first mixed with the following agents:

Water, deionized ml 9,000 Saponin solution ml 370 Diethylene glycol ml 370 Type 6 agent 4B (11% formaldehyde water solution) ml Hydroquinone, dry gm Sodium sulfite, dry gm 22 The sodium hydrosulfite and the sodium sulfite in emulsion E act as reducing agents to reduce the silver sulfate to colloidal silver nuclei which is deposited, together with the accelerator, on a sheet of paper as the paper is passed through the emulsion E to form the positive paper.

The emulsion 0 of the negative N is quickly permeated by the processing solution 10 so that upon contact with the positive emulsion E of the positive P there is an immediate diffusion of soluble silver salts from emulsion 8 to positive emulsion E. There is a very close cooperation between the processing solution and these emulsions to give this prompt diffusion and incident with the diffusion there is a darkening of the diffused silver salts within the layer of emulsion E. This darkening begins immediately with the diffusion and continues and i intensified by the added agent as above set forth so that there is a miniminn time required for the production of the positive from the negative. The emulsions after processing and contact with each other only need to remain together some twenty seconds in order to give a very deep and satisfactory positive from the usual negative. After pressing between the squeeze rolls 14 the positive is damp but sufficiently dry for use within a fraction of a minute.

The entire procedure for a given reproduction is completed well within one minute and the operations involved are simple, requiring no special skill or experience.

The MS3 dye in the negative emulsion is of the carbocyanine type for panchromatic sensitivity. Saponin solution is a spreading agent. Diethylene glycol is a plasticizer. The chrome alum and the formaldehyde solutions are, of course, hardeners; and the potassium dichromate eliminates the spreading of any iron spots appearing in the paper stock. In the positive emulsion the silver is important in the ultimate darkening of the emulsion in that it provides the necessary silver ingredient cooperating with the accelerator or intensifier.

In the preparation of the processing solution the presence of nitrogen serves as a protection against unnecessary oxidation. Sodium sulfite sulfite is also an antioxidant and this is its function in the positive emulsion where it is present in only sufiicient amount to serve this purpose. Sodium thiosulfate is a solvent used only as a fixer and clearer. In the solution, sodium hydroxide is an alkalizing agent.

It is important in the working of the process to avoid thorough wetting of the paper stock, which would require a protracted drying of the positive and correspondingly lengthen the time required. It is also critical to apply a progressive pressure, as by squeeze rolls, in the contacting of the emulsions so as to locally concentrate this presure and evenly apply it and the presed emulsion films cannot remain in contact for any substantial length of time without a very dangerous tendency of these films to adhere to each other, the films themselves being speoially composed for quick diffusion between them and prompt separation upon completion of the diffusion.

The squeegee action of the rollers combined with the superficial wetting of the paper fibers condition the positive P for quick drying. Within a minute it is merely damp and sufliciently dry for use and thorough drying requires only a matter of minutes.

The processing steps individually and combined are efficient and eflictive. No separate development of the negative is required since both the negative and positive are wet and processed together. This compacting of emulsion treatments to overlap and develop and diifuse and transfer and intensify simultaneously in a single passage of the papers is of the greatest importance in the successful application of the process in practical use.

Having thus described my invention, 1 claim:

1. A photographic sheet for use as a positive in the diffusion transfer reversal photocopying process having a gelatinous coating on one surface thereof, said coating embodying colloidal silver nucleii and Z-amino-S-mercapto-1,3,4-thiadiazole.

2. The method of making a photographic sheet for use as a positive in the diffusion transfer reversal photocopying process which comprises admixing a silver salt, sodium hydrosulfite and gelatin to form a coating, adding 2- amino-S-mercapto-l,3,4-thiadiazole to said solution, and coating a sheet of paper With said solution.

3. A diffusion transfer reversal photocopying process which comprises Wetting a photographic negative sheet and a photographic positive sheet with a developing solution containing a silver halide fixer and a silver halide developer, one face of said photographic negative sheet having a gelatinous coating embodying an exposed undeveloped silver halide prior to said Wetting and one face 6 of said photographic positive sheet having a gelatinous coating embodying colloidal silver nucleii and Z-amino- S-mercapto-1,3,4-thiadiazole, pressing said Wetted sheets together in face to face relationship so that the surfaces of said individual coatings are in intimate contact, thereby produoing a fully developed image on said coating of said photographic positive sheet, and separating said sheets.

References Cited in the file of this patent UNITED STATES PATENTS 2,532,014 Rott June 20, 1944 2,657,618 Eisbein Nov. 3, 1953 2,661,293 Land Dec. 1, 1953 2,689,180 Friedman Sept. 17, 1954 FOREIGN PATENTS 124,625 Australia June 17, 1947 879,995 France Dec. 10, 1942 695,915 Great Britain Aug. 19, 1953 OTHER REFERENCES Photo-Lab-Index, quarterly supplement No. 40, pages 1341 and 13-42 (date approximately October 1949). 

3. A DIFFUSION TRANSFER REVERSAL PHOTOCOPYING PROCESS WHICH COMPRISES WETTING A PHOTOGRAPHIC NEGATIVE SHEET AND A PHOTOGRAPHIC POSITIVE SHEET WITH A DEVELOPING SOLUTION CONTAINING A SILVER HALIDE FIXER AND A SILVER HALIDE DEVELOPER, ONE FACE OF SAID PHOTOGRAPHIC NEGATIVE SHEET HAVING A GELATINOUS COATING EMBODYING AN EXPOSED UNDEVELOPED SILVER HALIDE PRIOR TO SAID WETTING AND ONE FACE OF SAID PHOTOGRAPHIC POSITIVE SHEET HAVING A GELATINOUS COATING EMBODYING COLLOIDAL SILVER NUCLEII AND 2-AMINO5-MERCAPTO-1,3,4-THIADIAZOLE, PRESSING SAID WETTED SHEETS TOGETHER IN FACE TO FACE RELATIONSHIP SO THAT THE SURFACES OF SAID INDIVIDUAL COATINGS ARE IN INTIMATE CONTACT, THEREBY PRODUCING A FULLY DEVELOPED IMAGE ON SAID COATING OF SAID PHOTOGRAPHIC POSITIVE SHEET, AND SEPARATING SAID SHEETS. 